Price spikes in SA at 23:35 with the switch-in of off-peak hot water

Not long after posting these comments yesterday evening, the price spiked up close to the price cap at 23:35 (NEM time) as a result of approximately 200MW of off-peak electric hot water demand switching back in through South Australia.

This screenshot from NEM-Watch was automatically recorded at the time, and emailed to us as a record of the event:

The spot price spikes in South Australia coincident with the switch-in of off-peak electric hot water

Using ez2viewAustralia to generate a custom graph, we are able to show price and demand (and available generation) on the same chart to highlight what happened:

A trend of SA region data showing the price spike when off-peak electric hot water switches in

We can clearly see a jump in SA regional demand target at 23:35 in excess of 200MW coincident with the price spiking up towards the Market Price Cap.  This jump in demand is the result of the timed switch-in of off-peak electric hot water.

In the ez2view South Australian regional view (under Time Travel), we can see that:
1)  The wind farms had continued in the doldrums, with output barely registering in SCADA readings at the time of the price spike; and
2)  Pelican Point had wound back its output within the prior half-hour leading up to the price spike.
3)  We see Hallett GT and Dry Creek amongst the plants that increased their output to match the increase in demand.

A view of the SA region with the price spiking in line with the demand jump

That’s all we’ve got time to look at this morning.

About the Author

Paul McArdle
One of three founders of Global-Roam back in 2000, Paul has been CEO of the company since that time. As an author on WattClarity, Paul's focus has been to help make the electricity market more understandable.

3 Comments on "Price spikes in SA at 23:35 with the switch-in of off-peak hot water"

  1. It’s a pity that the offpeak load isn’t staggered. I guess ETSA have no incentive to do so.
    It only takes 4 hours to charge a hot water system from cold, and 2 from warm, so there’s plenty of play in the timing.

    • Possibilities like these intrigue us, Tom – and we’ll look further into them when we have the time. At present we don’t know what the barriers might be to prevent this happening.

  2. “It’s a pity that the off-peak load isn’t staggered.” – –
    I agree – how much discount would I win for a 2am start ? – I only heat the top half of the tank to 50*c for a hot morning shower- the thermostat range is 50 to75* – low pressure solar Beasley –
    Perhaps ETSA’s “J” meters should have a built-in 3hr random number generator [1/180] – we live in a digital world now – – cheers.

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